“Imagine a university’s basketball players striking before a Sweet Sixteen game demanding shorter practices, bigger dorm rooms, better food, and no classes before 11 a.m. This is an absurd decision that will destroy intercollegiate athletics as we know it,” Alexander said.

Northwestern has 19 varsity sports teams and about 500 student athletes. The football teams is made up of 112 players, including 85 scholarship athletes who would be eligible to unionize.

The university's former quarterback, Kain Colter, led the push for players to unionize. He helped form the College Athletes Players Association, which is vying to represent the team.

"The NCAA invented the term student athlete to prevent the exact ruling that was made today," Huma Ramogi, president of the College Athletes Players Association, told ESPN.com. "For 60 years, people have bought into their notion that they are students only. The reality is, players are employees and today's ruling confirms that. The players are one giant step closer to justice."

Northwestern said it would appeal the regional director's decision to the NLRB's full board, in a statement it released shortly after the ruling. The school has until April 9 to do so.

"While we respect the NLRB process and the regional director's opinion, we disagree with it," the school wrote. "Northwestern believes strongly that our student-athletes are non employees, but students. Unionization and collective bargaining are not the appropriate methods to address the concerns raised by student-athletes."

During the NLRB's hearing process in February, Northwestern argued that unions would hurt the sport of college football by encouraging the players to strike and the school to lock them out.

But Ohr found that the players' time commitment and performance-based scholarships were reasons to consider the student athletes as employees.

During training camp when school is not in session, the players spend about 50 hours to 60 hours each week practicing, Ohr noted. Once the season begins and they have to focus on classes, they spend about 40 hours to 50 hours on football-related activities.

Ohr noted that Northwestern's football team made more than $8 million in profits during the 2012-2013 season, none of which went to the players other than through scholarships.

The scholarship athletes typically receive about $61,000 each year in student aid. NCAA rules forbid players from receiving any other sort of payments for their services.

"Players are prohibited from profiting off their image or reputation, including the selling of merchandise and autographs," Ohr noted. "Players are also required to sign a release permitting the employer and the Big Ten Conference to utilize their name, likeness and image for any purpose."